JP2573289B2 - Solder wire-containing flux sheet, method of manufacturing the same, and soldering method using the solder wire-containing flux sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a solder sheet-containing flux sheet used for mounting, for example, an electronic component having leads on a printed board.

(Prior Art) In recent years, technology for forming electronic components by integrating semiconductor elements at high density has been remarkably advanced. For example, in a QFP (Quad Flat Package) -type IC (QFP) that projects multiple leads from a square package in four directions, the pitch between the leads is gradually reduced from 0.65 mm to 0.5 mm and then to 0.4 mm. Is coming. In addition, TAB (Tape Automated B
The pitch between leads, such as thin packages for onding) and liquid crystal modules, is 0.25-0.2 mm, which is very narrow compared to the QFP.

As described above, when the pitch between the leads of the electronic component is reduced (for example, when the pitch is 0.8 mm or less), soldering defects such as a solder bridge, an excessive amount of solder are insufficient, and the like. Has a significant effect on

In the case of thin TAB packages and liquid crystal modules, it is almost impossible to join them using conventional soldering methods. Utilization of conductive materials has been made.

However, this anisotropic conductive film is largely affected by thermal factors, that is, the material tends to undergo thermal expansion or denaturation due to heat, and the insulating properties are unstable and storage is difficult. For this reason, it has the disadvantage that the reliability of bonding is low. In addition, the anisotropic conductive film has a complicated fixing method such as securing a space for clipping, and the use of the anisotropic conductive film is limited to a micro current circuit.

(Problems to be Solved by the Invention) As described above, in recent years, the pitch between leads of electronic components has been rapidly miniaturized. There were many occurrences and there were many soldering corrections.

In addition, anisotropic conductive films are used to join electronic components with extremely fine pitches between leads. There are various restrictions such as being limited to

An object of the present invention is to provide a soldering method capable of soldering and connecting an electronic component to a printed board without excessive or insufficient amount of solder or solder bridging, and regardless of the pitch between leads. Is in
Another object of the present invention is to provide a flux sheet used in the soldering method and a method for manufacturing the same.

[Configuration of the invention]

(Means and Actions for Solving the Problems) In order to achieve the above object, the present invention provides a plurality of solder wires arranged in parallel at a predetermined interval and a sheet filled between the plurality of solder wires. It is intended to provide a solder sheet-containing flux sheet, comprising: a solidified flux; and a release paper adhered to at least one surface of the flux, wherein the release paper has an adhesive surface side. And a flux for sticking release paper having a higher viscosity than the above flux.

In addition, the method for manufacturing a solder sheet-containing flux sheet of the present invention includes a first step of positioning and fixing a plurality of solder wires in a container in parallel, and a step of pouring a molten flux into the container so as to interpose the solder wires. A second step of filling, and a third step of solidifying the flux poured into the container.
And a step of:

Further, the present invention further provides positioning and placing the solder wire-containing flux sheet between an electronic component and a printed board to which the electronic component is to be soldered with the release paper removed. An object of the present invention is to provide a method of soldering a flux sheet containing solder wires, wherein the electronic component is soldered to the printed board by heating and melting the flux sheet.

When the flux sheet constructed as above is removed with the release paper removed, for example, by heating with a resistance heating method, the flux is promoted by the melting of the flux and the solder wire is melted. Since the lead and the conductive pattern of the board are sandwiched by the same amount of solder for each lead and can be soldered by the action of surface tension, they can be joined at the same time without excessive or insufficient amount of solder or solder bridges.

(Example) Hereinafter, an example of the present invention is described based on a drawing.

FIG. 1 shows a flux sheet 2 including a plurality of solder wires 1... Arranged in parallel at a predetermined interval. The method of manufacturing the flux sheet 2 is as follows.

First, as shown in FIG. 2 (a), a plurality of solder wires 1 are arranged in parallel at regular intervals on the inner bottom 4 of a container 3 of a box made of stainless steel or the like. The solder wires 1 are cut to a length substantially equal to the depth of the pair of side walls 3a, 3a of the container 3, and are arranged and fixed in parallel with the side walls 3a, 3a. At this time, solder wires 1 ...
In other words, as shown in FIG. 2 (a), by providing grooves 5 so as to correspond to the outer diameter of the solder wires 1, the solder wires 1 are positioned at desired intervals and arranged in parallel. Can be easily put on. Next, in the container 3 in which the solder wires 1 are arranged, the solder wires 1 are filled so that there is no gap between them. Also, although not shown, until the depth substantially matches the solder wire diameter (flux). Pour liquid flux 6 (until sheet thickness approximately matches solder wire diameter).

Here, the flux 6 contains an active component, a nonvolatile component, and a special effect component as main components.
It contains a solvent and a workability controlling component as auxiliary components. The active components include aniline hydrochloride, trietatolamine hydrochloride, and triethylenetetramine hydrochloride to remove the oxide film and maintain the bonding time, and the non-volatile components to protect oxidation and improve heat resistance. Rosin-modified synthetic resin and the like are mixed. Oleic acid, chlorendic acid, etc. are mixed in as a special effect component for flame retardancy. In addition, use an organic solvent for the solvent,
In addition, ditertiary butyl cresol or the like is mixed as a workability adjusting component to prevent oxidation, decrease surface tension, and prevent firing.

The flux 6 is further mixed with a thermoplastic resin (for example, vinyl chloride, polyether sulfone, or the like), and is liquefied by stirring at a constant temperature for a constant time.

The temperature and time at this time are determined by the mixing ratio of various components.

Next, as shown in FIG. 2 (b), the liquid flux 6 poured into the container 3 is solidified by hot-air treatment to form a sheet. As a result, the flux 6 has a thickness substantially matching the diameter of the solder wires 1.
A sheet having an outer shape substantially the same as the shape of the inner peripheral wall of the container 3 is completed. Even if the upper surface 7 of the solidified or solidifying flux 6 has uneven undulations, flatness can be easily obtained by sliding a roller (not shown) on the upper surface 7 in parallel with a constant pressure. . After that, the solidified flux 6 containing the solder wires 1...
Then, as shown in FIG. 1, release papers 8, 8 are adhered to almost all areas of both surfaces including the upper surface 7. At this time,
The solidified flux 6 has no viscosity enough to stick the release papers 8,8. Therefore, this release paper
A thin liquid flux (flux for sticking release paper) whose viscosity is increased by reducing the mixed amount of the solvent of the flux 6 is applied to the sticking surface side of the above. Since the applied flux of the release papers 8 and 8 has a high viscosity, the release papers 8 and 8 can be attached to the flux sheet 6 in a releasable manner. Here, FIG. 1 shows an external appearance state in which a part of the flux sheet 6 solidified by peeling off the corner 9 of one release paper 8 is exposed.

As described above, the flux sheet 2 containing the solder wire
Is manufactured. The flux sheet 6 can be mass-produced by extending the length of the container 3 so that the flux sheet 6 can be wound around a reel (not shown) and stored. It will be easier.

Next, a method of soldering an electronic component, for example, a QFP 11 to the printed board 12 using the above-mentioned solder sheet containing flux 2 will be described.

First, release sheet 8,
8 is removed, and then a part of the flux sheet 2 containing the solder wire is cut out in such a manner that the leads 13... That is, the length of the solder wires 1 is made to substantially match the length of the joints 13a of the leads 13 with the printed board 12,
Further, the flux sheet 2 is cut out using a cutter (not shown) or the like to a size such that the number of the solder wires 1 matches the number of the leads 13. At this time, solder wire 1
It is necessary to use the flux sheet 2 containing the solder wires manufactured so that the lead intervals of the lead wires 13 correspond to the lead intervals of the lead wires 13.

Then, four pieces of the flux sheet 2 are cut out so as to correspond to a group A of the leads 13 projecting in the same direction of the QFP 11. The release papers 8, 8 of the four flux sheets 2a... Cut out at a predetermined size may be removed after cutting out. Fig. 3 (a) shows the cut out flux sheet
2a are arranged so that each solder wire 1 is located at the center of the lower surface of the joint 13a of each lead 13. In this state, one surface of the flux sheet 2a
It shows that the adhesive is applied to the substrate. At this time, the flux sheets 2a are bonded to the leads A by using the adhesive force remaining on the surface after the release plate 8 is removed. Then, as shown in FIG. 3 (b), the QFP 11 is placed at a predetermined position on the printed circuit board 12 with the flux sheets 2a adhered thereto, and the leads 13 of the QFP 11 and the conductive patterns 14 Are opposed to each other with the flux sheets 2a interposed therebetween. At this time, the flux sheet
The other surface of 2a is adhered to the conductive patterns 14 by the remaining adhesive force. Thus, the QFP 11 is temporarily fixed on the printed board 12.

Next, the flux sheet 2a is heated to be melted. Heating at this time is performed by the resistance heating method in the case of the contact type, and by the VPS (Vapor Phase
Soldering, far-infrared reflow, or laser may be used as a heat source. By this heating, solder wire 1 ...
Flux 6 is melted, and the flux is further decomposed, and at the same time, the solder in the flux sheet 2a is melted and QFP1
One of the leads 13 is connected to the pattern 14 of the printed board 12 by soldering. When the flux sheet 2 containing the solder wire is applied to the QFP 11, it can be performed on all four sides simultaneously.

In the soldering performed in this manner, since a fixed amount of solder is uniformly applied to each of the leads 13..., There is no excess or shortage of the solder, and the action of a solvent containing various components improves the wettability of the solder. Therefore, the soldering can be performed without generating an excessive or insufficient amount of solder or generating a solder bridge.

Also, a plurality of leads 13 (and conductive patterns 14)
..) Can be soldered almost simultaneously, so that the soldering operation can be easily performed and the work can be performed quickly, thus improving the efficiency.

In addition, when performing the soldering operation, it is not necessary to consider the warpage of the printed board 12 and the parallelism of the leads 13 of the QFP 11, so that the workability and the yield are improved.

In this embodiment, the cut-out flux sheets 2a.
It is temporarily fixed to the printed board 12 after bonding to the leads A of P11, but the present invention is not limited to this.
As shown in FIG. 4, the flux sheets 2a are first bonded to the conductive patterns 14 of the printed circuit board 12 in a state where the solder wires 1 correspond to each other.
You may make it adhere to a .... By doing so, there is no need to perform HAL (Hot Air Leveler) processing or solder paste printing, so equipment for this is not required.

In this embodiment, the case where the QFP 11 is soldered to the printed circuit board 12 has been described. However, the present invention is not limited to this, and other electronic components such as a semiconductor chip, a resistor, a capacitor, an inductor, Also, the present invention can be applied to the case of soldering a small transistor or the like.

The present invention is also applicable to a case where solder is buried in a through hole or a via hole, or to an inserted part.

It can also be applied to soldering structures other than electronic equipment.

〔The invention's effect〕

Since the present invention is configured as described above,
The following effects are obtained.

Since the soldering is performed using a solder sheet containing solder wires, which are provided in parallel at predetermined intervals and can be measured in advance, and a flux containing the above-mentioned solder wires containing various components, Soldering can be performed without causing an excessive or insufficient amount of solder or generating a solder bridge.

Also, since a plurality of solder wires can be melted almost simultaneously, the soldering operation can be performed easily and quickly, so that the quality is constant and the efficiency can be improved.

In addition, the above-mentioned flux sheet containing solder wires is formed by a method in which molten flux is poured into solder wires arranged in parallel in a container and solidified.
The manufacturing method is easy.

[Brief description of the drawings]

FIG. 1 is a perspective view of a flux sheet containing a solder wire, and FIG.
FIGS. 2A and 2B are side sectional views showing a manufacturing process of a flux sheet containing solder wires, and FIGS. 2A and 2B show a soldering method. 3
3A is a perspective view, FIG. 3B is a side view, and FIG. 4 is a perspective view showing a modification of the soldering method. 1 ... Solder wire, 2 ... Flux sheet with solder wire, 3
…… Container, 6 …… Flux, 8,8 …… Release paper, 11 …… QFP type
IC (electronic parts), 12 …… Printed circuit board.

Claims (4)

(57) [Claims] 1. A plurality of solder wires arranged in parallel at a predetermined interval, a flux filled between the plurality of solder wires and solidified into a sheet, and affixed to at least one surface of the flux. A flux sheet containing a solder wire, comprising a release paper. 2. The flux sheet according to claim 1, wherein the release paper is coated with a release paper sticking flux having a higher viscosity than the flux on the sticking surface side. 3. A first step of positioning and fixing a plurality of solder wires in a container in parallel, a second step of pouring a molten flux into the container and filling the space between the solder wires, And a third step of solidifying the flux that has flowed into the inside. 4. A flux sheet containing a solder wire according to claim 1 is positioned and placed between an electronic component and a printed board to which the electronic component is to be soldered, with the release paper removed. A soldering method using a flux sheet containing a solder wire, wherein the electronic component is soldered to the printed board by heating and melting the flux sheet containing the solder wire.